Injection molding method and system, and molded products manufactured thereby

ABSTRACT

Molding methods and systems are disclosed for manufacturing molded items ( 10 ) with an integral substrate ( 50 ) formed thereon, particularly wherein the substrate has a metallic appearance and/or wherein the molded product is formed with a geometric feature ( 66 ) associated with an edge of the substrate adapted for at least partially obscuring the edge in the molded product.

FIELD OF THE INVENTION

This invention relates to methods and apparatuses/systems for making aproduct. More particularly, the present invention relates to methods andapparatuses/systems for making a product by injection molding and tomolded products made thereby.

BACKGROUND OF THE INVENTION

Injection molding processes are well known, and generally involveinjecting a flowable material such as a plastic into a cavity preparedin a mold, and allowing the material to cool and harden to form aproduct that has a form generally complementary to that of the moldcavity.

In a variation of such processes, a film may be integrally formed on theproduct by inserting the film or substrate into the mold prior to theinjection of the molten material.

US2005/140055 discloses a method for making a part by injection moldingand decorating a visually-exposed face surface and a visually-exposedside surface of the part in their entireties during the injectionmolding of the part. The method includes the steps of providing a mold,inserting a decorative film into the mold, closing the mold, injecting amolten material into the mold causing the decorative film to conform tothe mold by virtue of the molten material, when filling the mold,exerting a force on the decorative film forcing the decorative film toabut intimately against the mold, hardening the molten material so as toform a hardened core, and forming the part with the decorative filmbeing adhered to the hardened core, by virtue of the decorative filmbeing possessed by the hardened core when the molten material hardensand becomes the hardened core, so as to allow the decorative film tocover the hardened core and thereby eliminate a concern for colorinconsistency of the hardened core caused by color variations of themolten material by virtue of the hardened core being covered by thedecorative film.

U.S. 2003/0122278 discloses a method for applying multiple decorativesheets of film to an injection-mold component as a part of the injectionmold process. Two sheets of film having desired images are permanentlyaffixed to the surfaces of the injection mold component as a part of theinjection molding process. An enhanced three-dimensional appearance isachieved by affixing the images to a transparent injection moldcomponent.

U.S. Pat. No. 4,052,497 discloses a method for the manufacture byinjection molding of articles composed of a plurality of layers of atleast three distinct materials coated one over the other. The methodincludes the steps of successive injection of a measured quantity of afirst material adapted to form the skin of the article, a measuredquantity of a second material to form the intermediate layer, and ameasured quantity of a third material to form the body of the article.The materials are introduced into the mold coaxially so as to give auniform distribution. The method is especially applicable to theproduction of articles in which the external and internal materials arejoined together by an intermediate material.

U.S. Pat. No. 4,686,076 discloses a method, machine, and mold forfabricating, by injection of synthetic material, containers having afilm forming an external coating. The machine includes a mold, aninjection nozzle, a film feed device, and apparatus for holding the filmagainst the male element of the mold. The injection nozzle is carried bythe male element of the mold and the holding apparatus includes a sliderin the cavity of the female element movable, under the action of themale element, against a return force.

U.S. Pat. No. 5,240,751 discloses a decorative automotive vehicle trimstrip and method and apparatus for forming by reshaping an end of apreviously extruded length of thermoplastic material. The surface of thelength of the thermoplastic material intended for viewing is maintainedat a cold temperature, well below the softening point of thethermoplastic material, during the reshaping operation. The length ofthe thermoplastic material is heated during reshaping by a mold sectionheated to 400 degrees F. to 410 degrees F. pressed against the surfaceintended to be affixed to the vehicle.

U.S. Pat. No. 5,415,536 discloses a method for forming a pattern onto anarticle during injection molding thereof. A pattern-bearing film isheated and softened by a heating board. The softened pattern-bearingfilm is transferred to the cavity surface of a female mold. Thereafter,the female mold and a male mold are closed. Then, a molten resin isinjected into the cavity. When the pattern-bearing film is brought intocontact with and heated by the heating board, marks or impressions ofair blow holes on the surface of the heating board remain on thepattern-bearing film. To prevent the formation of these marks orimpressions, a square-shaped holding frame is fixed on the surface ofthe heating board. The peripheral portion of the pattern-bearing film isheld on the surface of the holding frame. Thus, while the patternportion of the pattern-bearing film is spaced apart from the surface ofthe heating board, the film is heated. To keep the pattern-bearing filmuniformly spaced from the surface of the heating board, air is suppliedto the inside of the holding frame.

U.S. Pat. No. 6,090,336 discloses a method and apparatus formanufacturing an injection-molded article having an outer film on anexposed surface. The method includes securing the film about itsperiphery within a mold cavity prior to injection of molten materialinto the cavity. One way of securing the film is by applying vacuumpressure through peripheral holes in a frame surrounding the moldcavity. Molten material is injected into the cavity behind the film, andthe film slips from its initial position to be forced against a wall ofthe cavity by molten material being injected into the cavity. Theapparatus includes a frame for a molding apparatus adapted to initiallysecure the film in place prior to movement of the core block into placeand to permit the film to slip from its initial position to be forcedagainst the cavity wall as molten material fills the cavity.

U.S. Pat. No. 6,474,976 discloses a film holding apparatus for aninjection mold which is capable of surely holding a protective film on aspecific position of a mold surface of the injection mold. The filmholding apparatus for holding an inner film on the mold surface of theinjection molds consisting of two coupled molds havingsubstantially-vertical coupled surfaces thereof which includes twopositioning pins that can hang an upper edge side of the inner film onan upper edge portion of the mold surface of the mold, and upper andlower vacuum opening portions for film adsorption disposed so as tointerpose the positioning pins therebetween from the upper and lowersides. The upper vacuum opening portion is formed in a line whichextends along an upper edge of the mold surface.

SUMMARY OF THE INVENTION

Herein, “metallic layer” includes a layer, sheet, net, mesh, strips,foil or the like, made from a material or having a coating comprising ametal or metallic material, and/or comprising a material having theappearance of a metal or metallic material, wherein the “metallic layer”includes a material that is electrically conducting, as opposed to adielectric material including dielectric materials that may have ametallic-like appearance.

By “visually exposed” with respect to a surface of a part is meant asurface of the part that may usually be seen from particular desiredviewing directions when the part is in at least one intended position orlocation, or from the most common viewing direction for the part. Forexample, if the part is a box or bin cover that is normally closed, thevisually exposed surface thereof may be the upper surface of the cover,this being seen from the regular viewing directions, as opposed to theunderside of the cover, which may only be seen when the cover is in theopen position or from inside the box or bin.

According to a first aspect of the invention, a manufacturing method isprovided, comprising:

providing a substrate, comprising at least one electrically conductinglayer overlaid with at least one dielectric outer-facing layer, andfurther comprising an inner-facing surface;

applying an electrostatic charge to said outer-facing layer;

electrostatically holding said substrate in a desired position within amold cavity;

injecting a suitable molten material into said mold cavity in a mannersuch that at least a layer of said molten material possesses saidsubstrate via said inner-facing surface.

The visually exposed surface has a metallic appearance.

In particular, a method for manufacturing molded items having at leastone visually exposed surface is provided, comprising:

(a) providing a mold having a molding surface generally complementary tosaid visually exposed surface;

(b) providing a substrate, comprising at least one electricallyconducting layer overlaid with at least one dielectric outer-facinglayer, and further comprising an inner-facing surface;

(c) applying an electrostatic charge to said outer-facing layer;

(d) electrostatically holding said substrate in a desired positionwithin said mold such that said outer-facing layer is in at leastpartial abutment with said molding surface;

(e) injecting a suitable molten material into said mold in a manner suchthat at least a layer of said molten material is formed in overlyingrelationship with said inner-facing surface; and

(f) allowing the molten material to solidify and possess said substrate.

Optionally, the substrate may further comprise a dielectric inner-facinglayer defining said inner-facing surface.

The electrically conducting layer may comprise a metallic material,including for example a metallic foil. The electrically conducting layermay comprise at least one opening therethrough or may be substantiallycontinuous. The electrically conducting layer may comprise a metal or analloy including at least one of: aluminium, silver, oxidized silver,gold, titanium, copper, tin, steel, stainless steel, galvanized steel,nickel, magnesium.

The outer-facing layer may have a thickness of between about 30 micronand about 400 micron; the electrically conducting layer may comprise athickness of between about 5 micron and about 15 micron, or betweenabout 15 micron and about 30 micron, or greater than about 30 micron.

Optionally, step (c) comprises holding the substrate in a configurationgenerally corresponding to the form to be adopted by the substrate instep (f), providing a ground reference surface facing said inner-facingsurface, and establishing a suitable electric field between an electriccharger and said ground reference surface. Optionally, the substrate maybe configured in the form of a loop, including, for example, acylindrical loop, frustroconical loop, etc.

In step (e), the molten material may be injected into the mold causingthe substrate to conform to the mold surface by virtue of the moltenmaterial, when filling the mold, exerting a force on the substrateforcing the substrate to abut intimately against the mold surface.

Optionally, the mold may be in particular configured for forming ageometric feature in an item molded therein, said feature beingassociated with an edge of said substrate and adapted for at leastpartially obscuring said edge. The geometric feature may comprise arecess in the molded item, wherein said substrate edge is located atleast partially projecting into said recess. Alternatively, thegeometric feature may comprise a raised step formed on a visuallyexposed surface of said molded item, wherein said substrate edge islocated in close proximity to said step.

According to the second aspect of the invention, a method formanufacturing molded items having at least one visually exposed surfaceis provided, comprising:

providing a mold having a molding surface generally complementary tosaid visually exposed surface;

providing a substrate, comprising said at least visually exposed surfaceand an inner-facing surface;

holding said substrate in a desired position within said mold with saidvisually exposed surface facing said mold surface, and injecting asuitable molten material into said mold in a manner such that at least alayer of said molten material is formed in overlying relationship withsaid inner-facing surface, and allowing the molten material to solidifyand possess said substrate;

wherein said mold is configured for forming a geometric feature in anitem molded therein, said feature being associated with an edge of saidsubstrate and adapted for at least partially obscuring said edge.

The geometric feature may comprise a recess in the molded item, whereinsaid substrate edge is located at least partially projecting into saidrecess, or alternatively a raised step formed on a visually exposedsurface of said molded item, wherein said substrate edge is located inclose proximity to said step.

The substrate may comprise at least one electrically conducting layeroverlaid with at least one dielectric outer-facing layer, and furthercomprising an inner-facing surface, wherein said outer-facing surfacecomprises said visually exposed surface. Optionally, the substrate mayfurther comprise a dielectric inner-facing layer defining saidinner-facing surface. Alternatively, the substrate may be a dielectricsubstrate.

Thus, the substrate may be fully dielectric or may comprise at least oneat least one electrically conducting layer.

The invention also relates to molded items manufactured according to themanufacturing process of the invention. The item may comprise, by way ofnon-limiting example, a cylindrical form, a frustoconical form, asubstantially box-like form, and so on. The item may comprise, by way ofnon-limiting example, any one of bathroom furniture and accessories,home storage boxes, kitchen furniture and accessories, vehicleaccessories, and the like. The item may comprise, by way of non-limitingexample, any one of bins, toilet brush containers, toilet tissuedispensers; vehicle body trims, wheel hub covers, side mirror housings,and the like.

The present invention also relates to a system for manufacturing moldeditems having at least one visually exposed surface, comprising:

a mold having a molding surface generally complementary to said visuallyexposed surface;

a substrate, comprising at least one electrically conducting layeroverlaid with at least one dielectric outer-facing layer, and furthercomprising an inner-facing surface;

an electric charging device adapted for applying an electrostatic chargeto said outer layer;

a positioning mechanism for positioning a substrate within the mold suchto enable the substrate to be electrostatically held in a desiredposition within said mold such an outer charged layer thereof may be inat least partial abutment with said molding surface;

an injector arrangement for injecting a suitable molten material intosaid mold in a manner such that at least a layer of said molten materialis formed in overlying relationship with said inner-facing surface.

Optionally, the system further comprises a magazine having a stack ofsaid substrates, and wherein said positioning mechanism is furtheradapted for taking a single substrate at a time from said stack andtransporting the same to the mold.

According to aspects of the invention, molding methods and systems aredisclosed for manufacturing molded items with an integral substrateformed thereon, particularly wherein the substrate has a metallicappearance and/or wherein the molded product is formed with a geometricfeature associated with an edge of the substrate adapted for at leastpartially obscuring the edge in the molded product.

According to the invention, a wide variety of articles of manufacturemay be provided, having a visually desirable and realistic/authenticmetallic finish, and at the same time avoiding undesirable consequencesthat may sometimes arise when similar articles are manufacturedprimarily from metals. Examples may include bathroom furniture andaccessories including for example bins, toilet brush container, toilettissue dispenser; kitchen furniture and accessories; vehicleaccessories, for example trims, wheel hub covers, side mirror housingsetc. Many such articles, when made primarily from a metal, may besusceptible to denting, rusting or other problems, or may be undesirablyheavy or costly. The present invention provides such articles made froma plastic material or other material that may be used in aninjection-molding process, but including a visually exposed metalliclayer embedded therein, providing a desirable metallic finish to suchproducts.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carriedout in practice, embodiments will now be described, by way ofnon-limiting example only, with reference to the accompanying drawings,in which:

FIG. 1 is an isometric view of an embodiment of an article manufacturedaccording to the invention.

FIG. 2 a shows in cross-sectional view a portion of the article of FIG.1, including details of an embodiment of a substrate according to theinvention.

FIG. 2 b shows the substrate of FIG. 2 a having a generally rectangularplanform.

FIGS. 3 a to 3 d illustrate various steps in the manufacture of a partof the embodiment of FIG. 1

FIG. 4 illustrates a step in the manufacture of another part of theembodiment of FIG. 1

FIG. 5 illustrates, in partial cross-sectional view, a feature of partof the embodiment of FIG. 1, according to another aspect of theinvention.

FIG. 6 illustrates, in partial cross-sectional view, a feature ofanother part of the embodiment of FIG. 1, according to an aspect of theinvention.

FIG. 7 illustrates, in partial cross-sectional view, another embodimentof an article manufactured according to the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

A first embodiment of an item of manufacture produced according to theinvention, designated with the numeral 10 and referred to hereininterchangeably as an “article”, “part” or “product”, is illustrated inFIG. 1. The product 10 according to this embodiment may be, by way ofnon-limiting example, a closable bin, having a lower container part 20of general cylindrical form having a length dimension L and an outerdiameter D defining a fillable volume V, and a lid 30 that is hingedlyor otherwise releasably coupled to the lower part 20. The lower part 20has a visually exposed cylindrical surface 21 of particular interest andan upper rim 25, and is mounted onto a base 23. The lid 30 comprises avisually exposed flat or convex disk-like surface 31 of particularinterest and annular rim 33.

According to a first aspect of the present invention, a method andsystem are provided for manufacturing parts 20 and 30 via a novelinjection molding process, wherein said visually exposed surfaces 21 and31 may have a metallic appearance.

The metallic appearance of visually exposed surfaces 21 and 31 isobtained by individually injection-molding each of the parts 20, 30 inturn, each with a suitable substrate 50 held in place within thecorresponding mold, as will be described in greater detail herein.Referring to FIG. 2 a, the substrate 50 comprises an electricallyconducting metallic layer 55 laminated or otherwise sandwiched betweenan outer-facing electrically insulating dielectric layer 51 and aninner-facing electrically insulating dielectric layer 53, bonded to themetallic layer 55 by layers or adhesive 52, 54, respectively.Optionally, the outer-facing surface of inner layer 53 and theinner-facing surface of outer layer 51 may be activated by any suitablemethod, for example a plasma, corona, flame or chemical treatment, toproduce a treated layer. Optionally, the outer layer 51 is scratchresistant, while the inner layer 53 is adapted for being possessed by amolten material used in an injection molding process, when in contacttherewith.

Thus, the outer layer 51 and the inner layer 53 are individually formed,and then bonded to the metallic layer 55 via adhesives, which optionallymay be thermo and/or UV cured, which optionally may be water based orsolvent based, and so on. Alternatively, the layers 51, 55, 53 may bebonded mechanically or via ultrasonic welding or in any other suitablemanner.

Alternatively, the layers 51, 53 may be otherwise bonded or formed overthe metallic layer 55, for example using suitable coating, thermoformingor printing techniques, etc. For example, the layers 51, 53 may beformed over the metallic layer 55 as a lacquer or coating (for examplePU, acrylic, cellulose, alkyd, and so on, which may be coated over themetallic layer 55 using any suitable method, for example by evaporationof solvents, self-cross-linking, thermo-curing, UV curing and so on.

Alternatively, the dielectric/metallic layer sandwich construction ofthe substrate 50 may be achieved by covering the inner-facing part ofouter layer 51 and/or the outer facing part of inner layer 53 withmetallic layers using a suitable electrochemical; process, for exampleby means of electrostatic powdering in cold and/or hot state; hardcoating in plasma chambers, etc.

Alternatively, the dielectric/metallic layer sandwich construction ofthe substrate 50 may be achieved by covering the metallic layer 55 withpolymers, for example via thermal processes, including, for example,heat transfer coloring processes, heat laminating processes, etc.

The metallic layer 55 may be in the form of a substantially continuousmetallic foil, or alternatively may comprise cutouts of any desireddesign, for example a decorative pattern or company logo, or the layer55 may be in the form of a net or mesh, and the layers 51, 55, 53 may bebonded together by heat welding or otherwise bonding the inner layer 53to the outer layer 51 to one another directly via the cutouts.

The outer layer 51 is preferably optically transparent, and optionallyshaded in any desired colour, to allow the colour (original or modifiedvia layer 51) and texture of the metallic layer to be readily seen viathe outer layer. The inner layer 53 may be transparent, translucent oropaque, and have any desired colour.

Optionally, further intermediate layers, which may be metallic or nonmetallic, may be provided in the substrate 50 to provide any desiredmetallic appearance in the surfaces 21 and 31.

By way of non-limiting example, the metallic layer 55 may comprise afoil made of any one of aluminium, silver, oxidized silver, gold,titanium, copper, tin, steel, stainless steel, galvanised steel, nickel,magnesium, or any other suitable metal, which may be in elemental metalor alloy form, for example. Optionally, the metallic layer 55 may beformed from a number of different metals suitably juxtaposed and/orsuperposed with respect to one another. Further by way of non-limitingexample, the metallic layer 55 may be between about 5 micron and about15 micron thick, or between about 15 micron and about 30 micron thick,or thicker than about 30 micron. The metallic layer 55 may optionally bepre-treated, for example coated with a suitable primer, adhesive, paint,etc, prior to being formed into said substrate 50 and/or prior to beingsubjected to injection molding according to the invention.

Further by way of non-limiting example, the substrate 50 may be betweenabout 60 micron and about 200 micron thick, or thicker than 200 micron;the inner layer 53 may be made from material that is suitable for use inplastic injection technology, in particular for intimately fusing withinjected plastic in contact therewith in a mold, during the moldingprocess, and may include, by way of non-limiting example, any one ofbi-oriented polypropylene (BOPP), for example about 20 to about 50micron thick, or from extrusion direction oriented polypropylene (OPP),for example about 20 to about 150 micron thick, or from castpolypropylene (CCP), for example about 30 to about 200 micron thick; theouter layer 51 may be made from polyethylene-terephthalate (polyester)(PET), for example about 12 micron thick, or up to about 200 micronthick, or greater, or from different other transparent polyesters (forexample PETG), or from poly-methyl-met-acrylate (Acrylic) (PMMA), forexample about 60 to about 70 micron thick, or up to about 200 micronthick, or up to about 400 micron thick or greater, or from PC or fromtransparent polyamides, for example PA-11, PA-12, PEBA, or fromPS-derivatives, including for example GPPS, SAN, MABS, SBS, K-resinsetc. of suitable thickness. The layer 51 may be both rigid and soft(e.g., transparent soft-touch TPE-s, TPV-s, based for example on PU-s,SBS-s, SEBS-s, etc.).

In particular, the outer layer 51 comprises a thickness sufficient toretain a suitable electrostatic charge, for example between about 30micron to about 200 micron, or greater, for example, for a duration of afew seconds, for example, such as to enable the substrate 50 to beexternally charged and placed within a mold cavity, as will be explainedin greater detail herein. Such a thickness may range from between about30 micron to about 100 micron. Examples of suitable substrates 50 arecommercially available.

The part 20 and lid 30 may also each comprise other surfaces which arenot typically or are not intended to be visually exposed, at least mostof the time or from the desired viewing angles of the visually exposedsurfaces, and thus may constitute, for example, the inner-facingsurfaces of the part 20 and lid 30. Furthermore, there may be somevisually exposed surfaces, for example rims 25, 33 of part 20 and lid30, respectively, which may not necessarily comprise a metallicappearance.

The process for manufacturing part 20 according to one embodiment of theinvention will now be described. Referring to FIGS. 3 a to 3 d, a mold100 is provided for producing the item 10. The mold 100 comprises afirst, female mold part 110 and a second, male mold part 120 which maybe reversibly joined together to provide a mold cavity 130 in which thepart 20 may be formed. The cavity 130 thus has a size substantiallysimilar to, and a form or shape substantially complementary to, that ofthe item 20, optionally taking into account factors such as springback,shrinkage and so on, where appropriate, as is known in the art. Thefirst mold part 110 comprises a cavity 132 having a mold surface 122corresponding to the visually exposed surface 21, which in thisparticular example is substantially cylindrical. The second mold part120 comprises a mating portion 125, adapted for mating with matingportion 115 of the first mold part 110 at a parting line. The secondmold part 120 also comprises core 128, comprising cylindrical surface126 and end surface 127, substantially complementary to the unexposedinner surfaces of part 20. When the mold parts 110 and 120 are coupled,the core 128 is received in cavity 132, defining the mold cavity 130.

The mold part 120 further comprises at least one injection station 145,for example at the sides of the surface 126, or at the center of endsurface 127 (not shown), providing fluid communication between cavity130 and an injection material source (not shown), at least when the mold100 is closed and ready for use.

Optionally, the substrate 50 may be provided as pre-cut films, ready tobe used with mold 100. For example, and referring in particular to FIG.3 a, a magazine 160 may be provided holding a stack of superposedsubstrates 50, as is known in the art. A robotic arm 170, or othersuitable positioning mechanism, is provided, configured fortransporting, handling and positioning each substrate 50 in turn withrespect to the mold 100. The robotic arm 170 comprises an end-of-armtool 172 in the form of a mandrel or dummy 174, in this particularembodiment being in the form of a drum, having a number of suction ports173 arranged on the cylindrical surface of the dummy 174, and in fluidcommunication with a suitable suction source, for example a pump (notshown).

In operation, the dummy 174 may be brought into tangential proximitywith an edge 59 of substrate 50, which in this example is of a generalrectangular planform having two orthogonally arranged pairs of edges 59,58 (see FIG. 2 b). Edges 59 have a length substantially similar todimension L of the surface 21, and edges 58 have a length sufficient toenable the substrate to wrap around to form surface 21 of diameter D. Anair nozzle arrangement 162 blows a stream of air to separate anuppermost substrate 50 from the stack, and this substrate 50 may then begrasped by a suitable transport mechanism 165, which may comprise, forexample, suction pads, and transported towards the dummy 174 untiltangential contact is established therewith. A portion of the substrate50 close to edge 59 is then grasped by the dummy 174 by means of suctionports 173. The dummy 174 may be rotated about its axis 179 therebywinding the substrate 50 onto the cylindrical surface of the dummy 174,and held there via additional suction ports 173, the substrate 50 beingdisengaged from mechanism 165. Alternatively, the substrate 50 may belowered onto and draped over the dummy 174 using any suitable mechanism,and the suction ports 173 generate sufficient suction to wind thesubstrate onto the dummy. The substrate 50 is wound onto the dummy 174such that the outer-facing layer 51 is outermost, and the inner-facinglayer 53 is facing the cylindrical surface of dummy 174.

Next, the robotic arm 170 transports and positions the dummy 174generally coaxially coaligned with the cavity 132 of the mold part 110,and spaced therefrom by spacing s. Charging applicator 190 is providedfor applying an electrostatic charge to the outer-facing layer 51.Charging applicator 190 may be, for example, in the form of a chargingbar comprising a plurality of emitter pins or alternatively may be inthe form of a individual emitter modules; the style and number ofapplicators generally depends on the size and shape of the substrate 50,and the contours of the mold surface on which the substrate 50 is to beplaced. An electrically grounded reference surface, such as a groundedmetal plate, is provided in dummy 174, and may comprise the cylindricalsurface of the dummy. Optionally, a layer of antistatic foam materialmay be bonded to the cylindrical ground metal surface of the dummy 174.

Charging applicator 190 is operatively connected to a high voltage DCelectrical power supply, for example having a 30 kV adjustable outputcapacity, though in some embodiments, the charge required may be 15 to20 kV, for example, and positioned in the path of the dummy 174 suchthat as this is transported and aligned with respect to the cavity 132,an electrostatic charge is induced on the outer layer 51. The groundreference surface, generally facing the inner surface 53, attracts theelectric field from the charging applicator 190 and the outer layer 51of the substrate 50 becomes charged. For example the applicator 190 maybe positioned within spacing s or at any other suitable location.Alternatively, the applicator may be integrated with the end-of-arm tool172.

The outer layer 51 of the substrate 50 is thus charged externally withrespect to the mold or the dummy.

The charged substrate 50 is inserted into cavity 132 by the robotic arm170 such that the outer layer 51 is axially aligned with the surface122. The suction at suction ports 173 is terminated and the substrate 50is then attracted to and held on surface 122 by virtue of its charge,the mold part 110, or at least a portion thereof defining the cavity 132being electrically conducting and earthed at E. Optionally, air jets maybe provided, for example at the dummy 174, to blow the substrate towardsthe cavity 132. The robotic arm 170 is then removed, and the mold parts110 and 120 are mated, defining cavity 130 in which the substrate isappropriately aligned.

Referring in particular to FIG. 3 c, the injection process is theninitiated, molten material, typically a plastic material, in injectedinto cavity 130, via suitable injections stations 145 located on moldpart 120 and/or in mold part 110 (not shown), the injection stationsbeing located such as to inject molten material towards the inner layer53 of the substrate 50, while generally avoiding injecting moltenmaterial directly to the outer layer 51, particularly where thiscorresponds to the exposed surface 21. The molten material possesses theinner layer 53, and further the injection process also serves to pushthe substrate 50 into substantially full abutment with surface 122, ifthis was not already the case. Once the injection material 199 hassolidified, the substrate 50 is effectively integrally set with respectto the material 199, to form intermediate workpiece 20′, which may thenbe removed from the mold part 110 or from mold part 120, havingpreviously separated the mold parts 110 and 120. The same or a differentrobotic arm or positioning mechanism may be used for removing theworkpiece 20′ from the mold 100, via a suitable end-of-arm toolconfigured for so doing.

Optionally, a static neutralising bar 195 (FIG. 3 a) may be provided inthe robotic arm path between the charging applicator 190 and themagazine 160, so that whenever a new substrate 50 is being picked up thedummy 174, and in particular the suction cups 173, may be electricallyneutralized, which helps to avoid electrostatic buildup at the suctioncups 173.

While the process above has been described with respect to forming acylindrical surface 21 on part 20, it may be applied, mutatis mutandis,to forming any other suitably-shaped surface, for example conical,frusto-conical, box-like, pyramidal, and so on, the substrate 50 beingshaped appropriately so as to form the desired three-dimensional formwhen possessed by the material 199 in the mold. Similarly, in such casesthe dummy 174 and the molding surface of mold 100 may also be shapedappropriately, for example, also conical, frusto-conical, box-like,pyramidal, and so on, respectively, particularly when the part is beingdesigned having walls of generally uniform thickness.

Suitable control means may be provided for automating the manufacturingprocess, and suitable surface resistivity meters may be incorporated inthe manufacturing system to check that sufficient charge is beingapplied to the substrate before the mold injection.

In a variation of the molding process, a substrate may be providedcomprising a metallic layer and an outer facing non-conducting layerbonded thereto, similar to substrate 50, mutatis mutandis, but withoutan inner non-conducting layer. In such a case, the molten material comesinto contact directly with the metallic layer, which may optionally bepre-treated as desired, for example having a coating of primer,adhesive, paint, etc., possessing the same during the injection process.In a variation of this process, where the metallic layer may be in theform of a net or mesh, or otherwise comprises openings exposing parts ofthe outer facing non-conducting layer to the molten material, theseparts may be possessed by the molten material during the injectionprocess.

The base 23, which may be fabricated separately, for example also viainjection molding, may be mounted onto workpiece 20′ to complete part20. In other embodiments, the intermediate workpiece is the final part.

Referring to FIG. 4, the process for manufacturing part 30 is similar tothat described for part 20, mutatis mutandis, with the following maindifferences. The substrate 50 is now disc-shaped, and the robotic arm170 comprises an end-of-arm tool in the form of a suction head 174′comprising suction ports 173′ and adapted for transporting andpositioning the substrate in substantially flat form, rather than in alooped cylindrical form, into cavity 132′ of female mold part 110′,having been charged with static electricity via charger 190. The earthedmold part 110′ holds at least a part of the substrate in abuttingcontact with mold surface 122′, which corresponds to surface 31 of thepart 30, the substrate 50 having been released from the robotic arm.Subsequently, the mold 100′ is closed and material 199 is injected intothe mold cavity via one or more outlets 145′, pushing the substrate 50into the cavity 132′ such that the outer surface 51 is in substantiallyfull abutting contact with surface 132′. In particular the centralportion of the substrate 50 may be deformed to a mild convex form, andthe circular edge 57 of the substrate 50 may be deformed to pressagainst the generally cylindrical edge 123′ of surface 122′, to conformto such a particular form illustrated for the mold surface in FIG. 4.

According to another aspect of the invention, one or more free edges ofthe substrate 50 are visually hidden to some extent, and themanufactured item, for example corresponding parts 20, 30 are configuredfor this. This feature may help in effectively hiding from view possiblemisalignments between the substrate 50 and the desired or nominalposition that it is intended to assume with respect to the particularcorresponding molded part.

For example, referring to FIG. 5, the rim 25 of part 20 comprises aradially extending annular flange 61 having a circumferential lip 63depending therefrom in the axial direction towards the base 23, definingan annular recess 62 between surface 21 and the lip 63 of depth t. Deptht is dimensionally greater, axially, than the gap g that is expected tobe formed between edge 59 and the flange 61, including statisticallyacceptable variations in dimension g. Similarly, any overshoot of edge58 into the recess and onto the underside of flange 61 will also not bereadily apparent when viewing surface 21. Thus, when viewing part 20,edge 58 is effectively hidden from view via lip 63. By means ofnon-limiting example, depth t may be between about 0.3 to 13 mm, moreparticularly between about 1 mm and about 5 mm, and more particularlybetween about 2 mm and about 4 mm.

In another example, and referring to FIG. 6, an annular recess 66 isprovided between the surface 31 and the rim 33 of the lid 30. The recess66 is of a depth such that allows the edge 57 or disc-shaped substrate50 to be deformed into the recess to a variable depth during theinjection molding process, even allowing parts of the edge 57 toovershoot the bottom of the recess 66. The edge 57 is effectively hiddenfrom view, or at least not generally readily discernible, when viewingsurface 31 from any one of a variety of directions, being effectivelyhidden by the rim 33. By means of non-limiting example, the depth ofannular recess 66 may be between about 0.3 mm and about 5 mm, and moreparticularly between about 0.5 mm or about 1 mm and about 4 mm.

In yet another example, and referring to FIG. 7, the visual effect of asmall mismatch in alignment between the substrate and manufactured partmay also be effectively minimized by providing a stepped configurationat some of the visually exposed edges of the substrate with respect tothe part. In this figure, a container 200 according to anotherembodiment of the invention is illustrated, comprising a box-like bottompart 220 and a lid part 230. The lid part 230 comprises a generally flattop 241 and sides 242 depending therefrom, with a rim 233 circumscribingthe free edges of the sides 242. Corner portions 244 each comprisegenerally mutually orthogonal corner sides 252 and a corner top 251,which are protruding outwardly with respect to the corresponding sides242 and top 241, respectively, by a step Q. By means of non-limitingexample, the step Q may be between about 0.2 mm and about 5 mm,typically more particularly between about 0.3 mm or 0.5 mm an about 1 mmor 2 mm or 3 mm.

The visually exposed surface 231 of interest in this example is the top241 and sides 242, but not including the corner portions 244 or rim 233.Accordingly, a substrate may be possessed in situ within a mold duringthe molding process for the lid part 230, for example in a similarmanner to that described above for other embodiments of the inventionmutatis mutandis. In this case, though, the substrate may be of agenerally cruciform planform. Small misalignments between the concavecorners of the cruciform substrate and the edges of corner portions 244may result in some of the edges of the substrate overrunning onto stepsQ or not reaching steps Q, and the presence of the step Q itself can aidto mask this misalignment. A similar effect may be obtained between theother edges of the substrate and the rim 233, and thus a recess (notshown) may be provided in rim 233 where the sides 242 and/or 252 meetthe rim 233 for obscuring any misalignments between the correspondingedges of the substrate and the rim 233. The rim recess may be providedin addition to, or instead of, the stepped corner portions 244.

This aspect of the invention may be applied to substrates having ametallic appearance and comprising an electrically conducting materialtherein, for example substrate 50, or alternatively with fullynon-conducting substrates, including printed artwork, patterns etc.,mutatis mutandis, and using the method of injection molding according tothe invention, or any other suitable injection molding method in which asubstrate is placed in the mold before injection molding, mutatismutandis.

In the method claims that follow, alphanumeric characters and Romannumerals used to designate claim steps are provided for convenience onlyand do not imply any particular order of performing the steps.

Finally, it should be noted that the word “comprising” as usedthroughout the appended claims is to be interpreted to mean “includingbut not limited to”.

1-31. (canceled)
 32. A method of manufacture, comprising: (I) providinga substrate, comprising at least one electrically conducting layeroverlaid with at least one dielectric outer-facing layer, and furthercomprising an inner-facing surface; (II) applying an electrostaticcharge to said outer-facing layer; (III) electrostatically holding saidsubstrate in a desired position within a mold cavity; (IV) injecting asuitable molten material into said mold cavity in a manner such that atleast a layer of said molten material possesses said substrate via saidinner-facing surface.
 33. A method according to claim 32, wherein saidsubstrate further comprises a dielectric inner-facing layer definingsaid inner-facing surface.
 34. A method according to claim 32, whereinsaid electrically conducting layer comprises a metallic material.
 35. Amethod according to claim 32, wherein said electrically conducting layercomprises a metallic foil.
 36. A method according to claim 32, whereinsaid electrically conducting layer comprises at least one openingtherethrough.
 37. A method according to claim 32, wherein saidelectrically conducting layer is substantially continuous.
 38. A methodaccording to claim 32, wherein said electrically conducting layercomprises a metal or an alloy including at least one of: aluminum,silver, oxidized silver, gold, titanium, copper, tin, steel stainlesssteel, galvanized steel, nickel, magnesium.
 39. A method according toclaim 32, particularly for manufacturing molded items having at leastone visually exposed surface, wherein said mold cavity comprises amolding surface generally complementary to said visually exposedsurface, and wherein in step (III), said substrate in held in saiddesired position within said mold such that said outer-facing layer isin at least partial abutment with said molding surface.
 40. A methodaccording to claim 32, wherein said electrically conducting layercomprises a thickness of between about 5 micron and about 15 micron, ora thickness of between about 15 micron and about 30 micron, or athickness of between about 30 micron and about 400 micron.
 41. A methodaccording to claim 32, wherein step (IV) comprises allowing the moltenmaterial to solidify and possess said substrate.
 42. A method accordingto claim 32, wherein said electrically conducting layer comprises athickness greater than about 30 micron.
 43. A method according to claim32, wherein step (II) comprises holding the substrate in a configurationgenerally corresponding to the form to be adopted by the substrate instep (IV), providing a ground reference surface facing said inner-facingsurface, and establishing a suitable electric field between an electriccharger and said ground reference surface.
 44. A method according toclaim 43, wherein said substrate is configured in the form of a loop.45. A method according to claim 32, wherein in step (IV), the moltenmaterial is injected into the mold causing the substrate to conform tothe mold surface by virtue of the molten material, when filling the moldcavity, exerting a force on the substrate forcing the substrate to abutintimately against the mold surface.
 46. A method according to claim 32,wherein said mold is configured for forming a geometric feature in anitem molded therein, said feature being associated with an edge of saidsubstrate and adapted for at least partially obscuring said edge.
 47. Amethod according to claim 46, wherein said geometric feature comprises arecess in the molded item, wherein said substrate edge is located atleast partially projecting into said recess.
 48. A method according toclaim 46, wherein said geometric feature comprises a raised step formedon a visually exposed surface of said molded item, wherein saidsubstrate edge is located in close proximity to said step.
 49. A methodfor manufacturing molded items having at least one visually exposedsurface, comprising: (A) providing a mold having a molding surfacegenerally complementary to said visually exposed surface; (B) providinga substrate, comprising said at least visually exposed surface and aninner-facing surface; (C) holding said substrate in a desired positionwithin said mold with said visually exposed surface facing said moldsurface, and injecting a suitable molten material into said mold in amanner such that at least a layer of said molten material is formed inoverlying relationship with said inner-facing surface, and allowing themolten material to solidify and possess said substrate; wherein saidmold is configured for forming a geometric feature in an item moldedtherein, said feature being associated with an edge of said substrateand adapted for at least partially obscuring said edge.
 50. A system formanufacturing molded items having at least one visually exposed surface,comprising: (a) a mold having a molding surface generally complementaryto said visually exposed surface; (b) a substrate, comprising at leastone electrically conducting layer overlaid with at least one dielectricouter-facing layer, and further comprising an inner-facing surface; (c)an electric charging device adapted for applying an electrostatic chargeto said outer layer; (d) a positioning mechanism for positioning asubstrate within the mold such to enable the substrate to beelectrostatically held in a desired position within said mold such anouter charged layer thereof may be in at least partial abutment withsaid molding surface; (e) an injector arrangement for injecting asuitable molten material into said mold in a manner such that at least alayer of said molten material is formed in overlying relationship withsaid inner-facing surface.
 51. A system according to claim 50, furthercomprising a magazine having a stack of said substrates, and whereinsaid positioning mechanism is further adapted for taking a singlesubstrate at a time from said stack and transporting the same to themold.